Institute of Biology, Faculty of Sciences, 1Institute
of Physiology, Faculty of Medicine, University of Kragujevac,
Kragujevac and 2Institute for Biological Research
“Siniša Stanković”, Department of Physiology, Belgrade, Serbia
and Montenegro

Received April 22, 2003
AcceptedAugust 24, 2003

Summary
The effects of the sodium nitroprusside (SNP), a nitric oxide
(NO) donor clinically used in the treatment of hypertensive
emergencies on the energy production of rat reticulocytes were
investigated. Rat reticulocyte-rich red blood cell suspensions
were aerobically incubated without (control) or in the presence
of different concentrations of SNP (0.1, 0.25, 0.5, 1.0 mM). SNP
decreased total and coupled, but increased uncoupled oxygen
consumption. This was accompanied by the stimulation of
glycolysis, as measured by increased glucose consumption and
lactate accumulation. Levels of all glycolytic intermediates
indicate stimulation of hexokinase-phosphofructo kinase
(HK-PFK), glyceraldehyde 3-phosphate dehydrogenase (GAPD) and
pyruvate kinase (PK) activities in the presence of SNP. Due to
the decrease of coupled oxygen consumption in the presence of
SNP, ATP production via oxidative phosphorylation was
significantly diminished. Simultaneous increase of glycolytic
ATP production was not enough to provide constant ATP
production. In addition, SNP significantly decreased ATP level,
which was accompanied with increased ADP and AMP levels.
However, the level of total adenine nucleotides was
significantly lower, which was the consequence of increased
catabolism of adenine nucleotides (increased hypoxanthine
level). ATP/ADP ratio and adenylate energy charge level were
significantly decreased. In conclusion, SNP induced inhibition
of oxidative phosphorylation, stimulation of glycolysis, but
depletion of total energy production in rat reticulocytes. These
alterations were accompanied with instability of energy status.